OpenVMS Performance Management Order Number: AA–R237C–TE April 2001 This manual is a conceptual guide for experienced users responsible for optimizing performance on OpenVMS systems. For information about OpenVMS performance on AlphaServer GS80/160/320 systems, see the OpenVMS on AlphaServer GS-Series Systems Configuration and Performance Guidelines, available at http://www.openvms.compaq.com/gsseries/index.html. Revision/Update Information: This manual supersedes the OpenVMS Performance Management, OpenVMS Version 7.2. Software Version: OpenVMS Version 7.3 Compaq Computer Corporation Houston, Texas © 2001 Compaq Computer Corporation Compaq, VAX, VMS, and the Compaq logo Registered in U.S. Patent and Trademark Office. OpenVMS is a trademark of Compaq Information Technologies Group, L.P. in the United States and other countries. All other product names mentioned herein may be the trademarks of their respective companies. Confidential computer software. Valid license from Compaq required for possession, use, or copying. Consistent with FAR 12.211 and 12.212, Commercial Computer Software, Computer Software Documentation, and Technical Data for Commercial Items are licensed to the U.S. Government under vendor’s standard commercial license. Compaq shall not be liable for technical or editorial errors or omissions contained herein. The information in this document is provided "as is" without warranty of any kind and is subject to change without notice. The warranties for Compaq products are set forth in the express limited warranty statements accompanying such products. Nothing herein should be construed as constituting an additional warranty. The following are trademarks of Compaq Computer Corporation: Alpha, ACMS, DDIF, DECdirect, DECnet, HSC, and MicroVAX. The following are third-party trademarks: Motif and UNIX are trademarks of The Open Group in the United States and other countries. ZK6491 The Compaq OpenVMS documentation set is available on CD-ROM. Contents Preface ............................................................ xi 1 Performance Management 1.1 System Performance Management Guidelines ...................... 1–2 1.1.1 The Performance Management Process . ....................... 1–2 1.1.2 Conducting a Performance Audit ............................. 1–3 1.2 Strategies and Procedures ..................................... 1–4 1.3 System Manager’s Role ....................................... 1–5 1.3.1 Prerequisites ............................................ 1–5 1.3.2 System Utilities and Tools . ................................ 1–5 1.3.3 Why Use Them? . ........................................ 1–5 1.3.4 Knowing Your Work Load . ................................ 1–6 1.4 Developing a Strategy ........................................ 1–6 1.4.1 Managing the Work Load . ................................ 1–6 1.4.2 Distributing the Work Load . ................................ 1–7 1.4.3 Sharing Application Code . ................................ 1–8 1.5 Analyzing Complaints ........................................ 1–8 1.5.1 Preliminary Steps ........................................ 1–8 1.5.2 Hardware Problem ........................................ 1–8 1.5.3 Blocked Process . ........................................ 1–9 1.5.4 Unrealistic Expectations . ................................ 1–9 2 Performance Options 2.1 Decompressing System Libraries ................................ 2–1 2.2 Disabling File System High-Water Marking ....................... 2–2 2.3 Setting RMS File-Extend Parameters ............................ 2–2 2.4 Installing Frequently Used Images .............................. 2–2 2.5 Enabling File Caching ........................................ 2–3 2.6 Reducing System Disk I/O ..................................... 2–3 2.7 Tuning .................................................... 2–4 2.7.1 Prerequisites ............................................ 2–4 2.7.2 Tuning Suggestions ....................................... 2–4 2.7.3 Tools and Utilities ........................................ 2–5 2.7.4 When to Use AUTOGEN . ................................ 2–5 2.7.5 Adjusting System Parameter Values . ....................... 2–6 2.7.6 Using AUTOGEN Feedback . ................................ 2–6 2.7.7 Evaluating Tuning Success . ................................ 2–6 2.7.7.1 When to Stop Tuning . ................................ 2–7 2.7.7.2 Still Not Satisfied? ..................................... 2–7 iii 3 Memory Management Concepts 3.1 Memory ................................................... 3–1 3.1.1 Physical Memory ......................................... 3–2 3.1.2 Virtual Memory .......................................... 3–2 3.1.3 Process Execution Characteristics ............................ 3–2 3.2 Working Set Paging .......................................... 3–3 3.3 Process Swapping ............................................ 3–3 3.3.1 What Is the Swapper? . .................................... 3–3 3.3.2 Types of Swapping ........................................ 3–3 3.4 Initial Working Set Quotas and Limits ........................... 3–3 3.4.1 Processes . ............................................ 3–4 3.4.2 Subprocesses and Detached Processes ......................... 3–4 3.4.3 Batch Queues ............................................ 3–4 3.4.4 Required Memory Resources ................................ 3–5 3.4.5 User Programs ........................................... 3–5 3.4.6 Guidelines . ............................................ 3–5 3.5 Automatic Working Set Adjustment (AWSA) ....................... 3–6 3.5.1 What Are AWSA Parameters? . ............................ 3–6 3.5.2 Working Set Regions . .................................... 3–6 3.5.3 Adjustment Period ........................................ 3–7 3.5.4 How Does AWSA Work? .................................... 3–7 3.5.5 Page Fault Rates ......................................... 3–8 3.5.6 Voluntary Decrementing ................................... 3–11 3.5.7 Adjusting AWSA Parameters ................................ 3–12 3.5.8 Caution ................................................ 3–12 3.5.9 Performance Management Strategies for Tuning AWSA ........... 3–12 3.6 Swapper Trimming ........................................... 3–13 3.6.1 First-Level Trimming . .................................... 3–14 3.6.2 Second-Level Trimming .................................... 3–14 3.6.3 Choosing Candidates for Second-Level Trimming ................ 3–14 3.6.4 Disabling Second-Level Trimming ............................ 3–15 3.6.5 Swapper Trimming Versus Voluntary Decrementing . ........... 3–15 3.6.6 Virtual Balance Slots (VAX only) . ............................ 3–15 3.7 Active Memory Reclamation from Idle Processes . ................... 3–16 3.7.1 Reclaiming Memory from Long-Waiting Processes ................ 3–16 3.7.2 Reclaiming Memory from Periodically Waking Processes ........... 3–17 3.7.3 Setting the FREEGOAL Parameter ........................... 3–18 3.7.4 Sizing Paging and Swapping Files ............................ 3–18 3.7.5 How Is the Policy Enabled? ................................. 3–18 3.8 Memory Sharing ............................................ 3–19 3.8.1 Global Pages ............................................ 3–19 3.8.2 System Overhead ......................................... 3–22 3.8.3 Controlling the Overhead ................................... 3–22 3.8.4 Installing Shared Images ................................... 3–22 3.8.5 Verifying Memory Sharing .................................. 3–22 3.9 OpenVMS Scheduling ........................................ 3–23 3.9.1 Time Slicing . ............................................ 3–23 3.9.2 Process State ............................................ 3–23 3.9.3 Process Priority .......................................... 3–24 3.9.4 Priority Boosting ......................................... 3–25 3.9.5 Scheduling Real-Time Processes . ............................ 3–25 3.9.6 Tuning ................................................. 3–25 3.9.7 Class Scheduler .......................................... 3–25 3.9.8 Processor Affinity ......................................... 3–26 iv 4 Evaluating System Resources 4.1 Prerequisites ............................................... 4–1 4.2 Guidelines . ................................................ 4–2 4.3 Collecting and Interpreting Image-Level Accounting Data ............. 4–2 4.3.1 Guidelines .............................................. 4–2 4.3.2 Enabling and Disabling Image-Level Accounting . ............... 4–3 4.3.3 Generating a Report ....................................... 4–3 4.3.4 Collecting the Data ....................................... 4–3 4.4 Creating, Maintaining, and Interpreting MONITOR Summaries . ....... 4–6 4.4.1 Types of Output . ........................................ 4–6 4.4.2 MONITOR Modes of Operation .............................. 4–7 4.4.3 Creating a Performance Information Database . ............... 4–7 4.4.4 Saving Your Summary Reports .............................. 4–7 4.4.5 Customizing Your Reports . ................................ 4–7 4.4.6 Report Formats . ........................................ 4–8 4.4.7 Using MONITOR in Live Mode .............................. 4–8 4.4.8 More About Multifile Reports ................................ 4–8 4.4.9 Interpreting MONITOR Statistics ............................ 4–9 5 Diagnosing Resource Limitations 5.1 Diagnostic Strategy . ........................................ 5–1 5.2